Apparatus for filling open-ended containers with free-flowing powdered or granular material is well-known. These powdered or granular materials include a broad range of food products, including milk products, condiments, tea, coffee, sugar, salt, cocoa, rice and seeds, as well as a general chemical line, including cleansers, detergents, insecticides, drain and bowl cleaners, lyes, crystals, and the like. An apparatus of this general type is disclosed in U.S. Pat. No. 2,849,033, issued Aug. 26, 1958, to John R. Nalbach. Apparatus of this type has found a wide range of acceptance in the food industry, chemical industry, and cosmetic industry, for packaging all manner of dry material in powdered or granular form. In the course of the operation of the prior art apparatus, several problems with the apparatus have been observed. The prior art device utilizes a pair of starwheels in the operation of the apparatus. The starwheels operate in a satisfactory manner. However, there is a problem in the exact synchronization of the starwheel, which requires a highly-skilled mechanic; also, a problem of removal of filled containers from the machine. The more product in the container, the more likely it is to spill as the direction of movement of the container is changed sharply.
Another problem which occurs in the operation of any mechanical apparatus is that there is no absolute perfection. Oftentimes, containers may be slightly bent, or for some reason are not fed into the apparatus, so that a measuring flask filled with a powdered or granular material discharges its entire contents, not into a container, but into the machine. This requires the machine to be halted for cleaning purposes and, if there is a prolonged absence of containers, the machine has to be shut down completely for a thorough cleaning.
In order for the measuring flasks to operate properly, it is necessary for the material to be of the same density since the flasks operate on a volumetric principle. The head of the material which is to be filled determines the density. It is particularly desirable to have the same head in a filling tank, thus eliminating any variations in the quantity of material which is delivered into the containers.